<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
	<script type="text/javascript">
		
		var num1 = prompt('请输入第一个数字');
		var charset = prompt('请输入运算符，例如+-*/');
		var num2 = prompt('请输入第二个数字');
		
		var str = num1+charset+num2;
		var re = eval(str);
		document.write(re);
		
		
	</script>
	</head>
	<body>
	</body>
</html>
